Hmmm, yes this is a way too, but i was thinking about detecting the internet connection of a player....
Detecting different users that have "something" in their connection with Brainking the same, such thing that they should not have the same, then this would be an indication of multiple ID's....
Only an indication because of cource members of a family could use a computer and this is perfectly normal. But then, games of these users will easily show if they are actually cheaters or different persons........